Linguagem C - Relógio Digital

#include <windows.h>
#include "resource.h"

#define ID_TIMER 1

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hI, HINSTANCE hPI, PSTR szCL, int iCS) {
    static TCHAR szAppName[] = TEXT("DigClock");
    HWND   hwnd;
    MSG    msg;
    WNDCLASS wc;

    wc.style         = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hI;
    wc.hIcon         = LoadIcon(hI, IDI_ICON);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = GetSysColorBrush(3);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = szAppName;

    if(!RegisterClass(&wc)) {
        MessageBox(NULL, TEXT("Error!"), szAppName, MB_ICONERROR);
        return 0;
    }

    hwnd = CreateWindow(
        szAppName, TEXT("Relógio Digital"), WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
        NULL, NULL, hI, NULL
    );

    ShowWindow(hwnd, iCS);
    UpdateWindow(hwnd);

    while(GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
        FreeConsole();
    }
    return msg.wParam;
}

void DisplayDigit(HDC hdc, int iNumber) {
    static BOOL fSevenSegment[10][7] = {
        1, 1, 1, 0, 1, 1, 1, /**0*/
        0, 0, 1, 0, 0, 1, 0, /**1*/
        1, 0, 1, 1, 1, 0, 1, /**2*/
        1, 0, 1, 1, 0, 1, 1, /**3*/
        0, 1, 1, 1, 0, 1, 0, /**4*/
        1, 1, 0, 1, 0, 1, 1, /**5*/
        1, 1, 0, 1, 1, 1, 1, /**6*/
        1, 0, 1, 0, 0, 1, 0, /**7*/
        1, 1, 1, 1, 1, 1, 1, /**8*/
        1, 1, 1, 1, 0, 1, 1  /**9*/
    };
    static POINT ptSegment[7][6] = {
         7,  6, 11,  2, 31,  2, 35,  6, 31, 10, 11, 10,
         6,  7, 10, 11, 10, 31,  6, 35,  2, 31,  2, 11,
        36,  7, 40, 11, 40, 31, 36, 35, 32, 31, 32, 11,
         7, 36, 11, 32, 31, 32, 35, 36, 31, 40, 11, 40,
         6, 37, 10, 41, 10, 61,  6, 65,  2, 61,  2, 41,
        36, 37, 40, 41, 40, 61, 36, 65, 32, 61, 32, 41,
         7, 66, 11, 62, 31, 62, 35, 66, 31, 70, 11, 70
    };

    int iSeg;

    for(iSeg=0; iSeg<7; iSeg++)
        if(fSevenSegment[iNumber][iSeg])
            Polygon(hdc, ptSegment[iSeg], 6);
}

void DisplayTwoDigits(HDC hdc, int iNumber, BOOL fSuppress) {
    if(!fSuppress || (iNumber/10 != 0)) {
        DisplayDigit(hdc, iNumber/10);
    }
    OffsetWindowOrgEx(hdc, -42, 0, NULL);
    DisplayDigit(hdc, iNumber % 10);
    OffsetWindowOrgEx(hdc, -42, 0, NULL);
}

void DisplayColon(HDC hdc) {
    POINT ptColon[2][4] = {
        2, 21, 6, 17, 10, 21, 6, 25,
        2, 51, 6, 47, 10, 51, 6, 55
    };

    Polygon(hdc, ptColon[0], 4);
    Polygon(hdc, ptColon[1], 4);

    OffsetWindowOrgEx(hdc, -12, 0, NULL);
}

void DisplayTime(HDC hdc, BOOL f24Hour, BOOL fSupress) {
    SYSTEMTIME st;

    GetLocalTime(&st);

    if(f24Hour)
        DisplayTwoDigits(hdc, st.wHour, fSupress);
    else
        DisplayTwoDigits(hdc, (st.wHour%=12)?st.wHour:12, fSupress);

    DisplayColon(hdc);
    DisplayTwoDigits(hdc, st.wMinute, FALSE);
    DisplayColon(hdc);
    DisplayTwoDigits(hdc, st.wSecond, FALSE);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    static BOOL f24Hour, fSuppress;
    static HBRUSH hBrushRed;
    static int cxClient, cyClient;
    HDC         hdc;
    PAINTSTRUCT ps;
    TCHAR       szBuffer[2];

    switch(msg) {
        case WM_CREATE:
            hBrushRed = CreateSolidBrush(RGB(255, 0, 0));
            SetTimer(hwnd, ID_TIMER, 1000, NULL);

        case WM_SETTINGCHANGE:
            GetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_ITIME, szBuffer, 2);
            f24Hour = (szBuffer[0] == '1');

            InvalidateRect(hwnd, NULL, TRUE);
            return 0;

        case WM_SIZE:
            cxClient = LOWORD(lParam);
            cyClient = HIWORD(lParam);
            return 0;

        case WM_TIMER:
            InvalidateRect(hwnd, NULL, TRUE);
            return 0;

        case WM_PAINT:
            hdc = BeginPaint(hwnd, &ps);

            SetMapMode(hdc, MM_ISOTROPIC);
            SetWindowExtEx(hdc, 276, 72, NULL);
            SetViewportExtEx(hdc, cxClient, cyClient, NULL);

            SetWindowOrgEx(hdc, 138, 36, NULL);
            SetViewportOrgEx(hdc, cxClient/2, cyClient/2, NULL);
            SelectObject(hdc, GetStockObject(NULL_PEN));
            SelectObject(hdc, hBrushRed);

            DisplayTime(hdc, f24Hour, fSuppress);

            EndPaint(hwnd, &ps);
            return 0;

        case WM_DESTROY:
            KillTimer(hwnd, ID_TIMER);
            DeleteObject(hBrushRed);
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd, msg, wParam, lParam);
}

/********************Arquivo: resource.h********************/

#define IDI_ICON 13

/********************Arquivo: resource.rc********************/

#include "resource.h"
#include "afxres.h"

IDI_ICON ICON              "project1.ico"